CFC (chlorofluorocarbons) and HCFC (hydrochloro-fluorocarbons), which have conventionally been used as refrigerants for refrigerating apparatuses, have been subjected to regulation due to the problem of recent ozone layer depletion, and HFC (hydrofluorocarbons) have come to be used as refrigerants instead of CFC and HCFC.
Among HFC refrigerants, HFC-134a, which has normally been used as a refrigerant for automotive air conditioners, has an ozone depleting potential (ODP) of 0 but has a high global warming potential (GWP), and therefore has been subjected to regulation in Europe. Thus, the development of a refrigerant that replaces HFC-134a is an urgent need.
Under such a background, use of unsaturated fluorohydrocarbon refrigerants whose ODP and GWP are extremely small and whose thermodynamic properties, which are a measure of refrigerant performance, are equal to or higher than HFC-134a has been proposed as refrigerants that replace HFC-134a.
Moreover, in Patent Literature 1, for example, a refrigerating machine oil composition comprising: a base oil that comprises a polyol ester-based compound as a main component; a phosphorus-based additive consisting of a phosphoric acid triester and/or a phosphorous acid triester; and at least one acid scavenger selected from glycidyl esters, glycidyl ethers, and α-olefin oxides is disclosed as a refrigerating machine oil that can be used together with an unsaturated fluorohydrocarbon refrigerant and that can improve performances such as compatibility with unsaturated fluorohydrocarbon refrigerants, sealing properties, friction properties at sliding portions, and stability.